The invention relates to an inductively activatable firing capsule for the gas generator of a passenger restraint system in a motor vehicle as claimed in the preamble of claim 1.
One such firing capsule is known from U.S. Pat. No. 5,799,972 A. In this prior art a transformer is connected to the trigger circuit and electrically isolates the firing capsule from the trigger current source. GB 1 416 095 A describes a firing capsule in which the electrical energy necessary for the detonation process is likewise inductively coupled in. For this reason, outside the firing capsule there is a primary winding, while in the interior of the capsule there is a secondary winding. The two ends of the secondary winding spaced apart from one another dip into an electrically conductive igniting agent which is caused to explode by current flowing through it. Finally, U.S. Pat. No. 3,185,093 discloses an inductively activatable firing capsule for different applications in which the secondary winding within the capsule is applied to a core and the ends of the secondary winding are connected by a resistance wire which penetrates the igniting agent.
The object of the invention is to develop an inductively activatable firing capsule of the initially mentioned type such that misfires as a result of broken or corroded resistance wires are reliably avoided.
This object is achieved by the inductively activatable firing capsule with the features cited in claim 1. Advantageous developments and embodiments are given in the dependent claims.
The inventive idea is to replace the thin, fracture-endangered resistance wire of conventional firing capsules by an especially simple and at the same time invulnerable construction.
The invention is detailed below using embodiments.